RESUMO
The concentration of serum aluminum was measured by electrothermal atomic absorption spectrometry in 71 patients with intracranial tumors. The data were compared with those from a reference group of 15 healthy adult individuals. The serum concentrations of aluminum were significantly increased (p < 0.01) in patients with malignant gliomas and meningiomas. The concentrations of serum calcium, known as an antagonist of aluminum, were normal in the same patients.
Assuntos
Alumínio/sangue , Neoplasias Encefálicas/sangue , Neoplasias Meníngeas/sangue , Meningioma/sangue , Neoplasias Hipofisárias/sangue , Adenoma/sangue , Adulto , Astrocitoma/sangue , Neoplasias Encefálicas/secundário , Glioblastoma/sangue , Humanos , Neuroma Acústico/sangue , Valores de ReferênciaRESUMO
Vertebrate retinal photoreceptors recover from photoexcitation-induced hydrolysis of guanosine 3', 5'-monophosphate (cyclic GMP) by resynthesizing cyclic GMP, which reopens cation channels that have been closed by light. Activation of guanylate cyclase by light-induced depletion of cytosolic calcium is a key event in this recovery process. This cyclase has now been shown to be regulated by a 23-kilodalton calcium binding protein. The protein is present in both rod and cone photoreceptors and was named recoverin because it promotes recovery of the dark state. The amino acid sequence of recoverin exhibits three potential calcium binding sites (EF hands). That recoverin binds calcium was confirmed with calcium-45 and by observing calcium-induced changes in its tryptophan fluorescence. Recoverin activated guanylate cyclase when free calcium was lowered from 450 to 40 nM, an effect that was blocked by an antibody to recoverin. Thus, guanylate cyclase in retinal rods is stimulated during recovery by the calcium-free form of recoverin. A comparison of recoverin with other calcium binding proteins reveals that it may represent, along with the protein visinin, a family of proteins that are regulated by submicromolar calcium concentrations.
Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Cálcio/farmacologia , Proteínas do Olho , Guanilato Ciclase/metabolismo , Lipoproteínas , Proteínas do Tecido Nervoso , Células Fotorreceptoras/metabolismo , Segmento Externo da Célula Bastonete/metabolismo , Sequência de Aminoácidos , Animais , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/isolamento & purificação , Bovinos , Ativação Enzimática , Hipocalcina , Cinética , Dados de Sequência Molecular , Peso Molecular , Especificidade de Órgãos , Recoverina , Retina/citologia , Homologia de Sequência do Ácido NucleicoRESUMO
The authors have added selenium tablets to the diet of 15 patients with malignant brain tumors. In twelve patients with glioblastoma multiforme this treatment didn't prolong the postoperative survival. Further clinical observations are necessary to precise the usefulness of selenium in cases of low-grade gliomas.
Assuntos
Astrocitoma/tratamento farmacológico , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Cerebelares/tratamento farmacológico , Glioblastoma/tratamento farmacológico , Meduloblastoma/tratamento farmacológico , Selênio/administração & dosagem , Adulto , Astrocitoma/mortalidade , Astrocitoma/radioterapia , Astrocitoma/cirurgia , Neoplasias Encefálicas/mortalidade , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/cirurgia , Neoplasias Cerebelares/mortalidade , Neoplasias Cerebelares/radioterapia , Neoplasias Cerebelares/cirurgia , Criança , Terapia Combinada , Irradiação Craniana , Feminino , Seguimentos , Glioblastoma/mortalidade , Glioblastoma/radioterapia , Humanos , Masculino , Meduloblastoma/mortalidade , Meduloblastoma/radioterapia , Meduloblastoma/cirurgia , Complicações Pós-Operatórias/mortalidade , Taxa de Sobrevida , Vitamina E/administração & dosagemRESUMO
The concentrations of serum selenium were measured by atomic absorption spectrophotometry in 139 patients with tumors in cranium cavity. The data from patients were compared with those from a reference group of 294 healthy adult individuals. The serum concentrations of selenium is significantly decreased (p less than 0.001) in patients with malignant tumors. The authors discuss the possibilities for treatment of malignant tumours of central nervous system with selenium.
